Paper feeding cassette for image forming apparatus

ABSTRACT

A paper feeding cassette for an image forming apparatus includes an inclined supporter including an inclined plate fixedly disposed in a cassette body and a support plate for reciprocating, a separation guide including a fixing guide fixedly supported on the inclined plate and a moving guide movably supported on the support plate, and a reciprocating unit reciprocating the support plate. Accordingly, the moving guide selectively comes into contact with a sheet such that a friction resistance generated at a front end of the sheet varies in a degree in accordance with a type of the sheet.

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of Korean Patent ApplicationNo. 2002-2366, filed Jan. 15, 2002, in the Korean Intellectual PropertyOffice, the disclosure of which is incorporated herein by reference.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] The present invention relates to a paper feeding cassette for animage forming apparatus, and more particularly, to a paper feedingcassette removably mounted in an image forming apparatus to containsheets of paper to be printed therein and supply the sheets to an imageforming apparatus body one by one.

[0004] 2. Description of the Related Art

[0005] Referring to FIG. 1, an image forming apparatus, such as aphotocopier, a laser printer, a facsimile, and a multi-function device,has a paper feeding cassette 100 in which sheets of paper to be suppliedinto an image forming apparatus body are stacked. Generally, the paperfeeding cassette 100 is removably mounted in the image forming apparatusbody. The sheets stacked in the paper feeding cassette 100 are suppliedto the image forming apparatus body, one by one, by a pick-up unit.

[0006] Referring to FIGS. 2 and 3, the paper feeding cassette 100includes a cassette body 110, an inclined supporter 130 disposed insidethe cassette body 110 at a predetermined slope with respect to anuppermost sheet P, and a separation guide 120 being supported on theinclined supporter 130.

[0007] In the above construction, a pickup roller 140 rotates to be incontact with the uppermost sheet P stacked in the paper feeding cassette100 and pushes up the uppermost sheet P in a direction of “A”. Then, afront end of the sheet P comes into contact with the separation guide120. At this point, there is a roughness on a surface of the separationguide 120 to which the sheet P contacts. Accordingly, the sheet P isseparated one by one due to a friction resistance that is generated whenthe uppermost sheet P comes into contact with the surface of theseparation guide 120, and when the sheet P is slidably picked-up.

[0008] Recently, the image forming apparatus has been improved to becapable of performing a printing operation using various types of thesheet P. Accordingly, the paper feeding cassette 100 is available toaccommodate the various types of the sheet P.

[0009] However, the surface of the separation guide 120 to be in contactwith the sheet P is made of a material having a predetermined surfaceroughness, and the separation guide 120 is fixedly disposed in thecassette body 110. Accordingly, the sheet P is picked-up by the pickuproller 140 with the same friction resistance regardless of the type ofthe sheet P.

[0010] Accordingly, if the separation guide 120 is made of materialhaving a high surface roughness, it is effective in separating a thinsheet P one by one. However, in the same case, the separation guide 120has a difficulty separating a thick sheet P due to an increased frictionresistance, which is attributed to a self-weight of the thick sheet P.Thus, there are problems that the thick sheet P is not picked-up and isjammed in the cassette body 110.

[0011] On the other hand, if the separation guide 120 is made of anothermaterial having a low surface roughness, it has the effectiveness inseparating and picking up the thick sheet P one by one owing to thedecreased friction resistance. However, in the same case, since thefriction resistance is not generated sufficiently for the separationguide 120 to separate the thin sheet P one by one, there is a problemthat the thin sheet P is fed out in an overlapping relationship withother sheets P.

SUMMARY OF THE INVENTION

[0012] In order to solve the above and other problems in the relatedart, it is an object to provide a paper feeding cassette having aplurality of paper separation guides able to separate various types ofpaper one by one from a paper cassette.

[0013] Additional objects and advantageous of the invention will be setforth in part in the description which follows and, in part, will beobvious from the description, or may be learned by practice of theinvention.

[0014] In order to achieve the above and other objects, a paper feedingcassette for an image forming apparatus according to an embodiment ofthe present invention includes a separation guide disposed in thecassette body containing sheets therein in plural numbers and comes intocontact with a front end of the sheet being picked-up such that thereoccurs a predetermined friction resistance at a contacting area of theseparation guide and the sheet. At least one separation guide isdisposed to be able to contact selectively the front end of the sheet inaccordance with a type of the sheet.

[0015] Accordingly, the friction resistance between the picked-up sheetand the separation guide can vary in degree. Therefore, it is possibleto separate the sheets one by one regardless of the type of the sheetsstacked in the cassette body and supply the sheet to an image formingapparatus body of the image forming apparatus.

[0016] According to another embodiment of the present invention, thepaper feeding cassette for the image forming apparatus includes acassette body containing the sheets therein, an inclined plate fixedlydisposed in the cassette body to come into contact with a picked-upsheet, at least one fixing guide fixedly disposed in the cassette bodyand supported on the inclined plate, at least one moving guide movablydisposed at the inclined plate to move toward and away from a contactline where the fixing guide contacts the sheet, and a reciprocating unitlinearly reciprocating the moving guide.

[0017] The reciprocating unit includes a support plate movably disposedwithin a space formed between a rear surface of the fixing guide and asidewall of the cassette body to support the moving guide, a guideportion movably supporting the support plate in a sliding manner, a cammember rotatably disposed within the space to contact a rear surface ofthe support plate to reciprocate the support plate, and a resilientpressing member resiliently pressing one of the support plate and thecam member in a direction of a contact point of the support plate andthe cam member.

[0018] According to an aspect of the present invention, the inclinedplate is provided with at least one opening. It is possible that themoving guide selectively moves with respect to the contact line betweenthe sheet and the fixing guide through the opening in accordance with areciprocal movement of the support plate.

[0019] According to another aspect of the present invention, the cammember is disposed on a rotary shaft disposed across the space, and therotary shaft is rotated by a driving unit.

[0020] According to another aspect of the present invention, the drivingunit is a rotary lever disposed at an end of the rotary shaft extendedfrom the sidewall of the cassette body or an electromotive motordisposed inside the cassette body to be connected with the rotary shaftto transmit a rotation driving force to the rotary shaft.

[0021] According to another aspect of the present invention, theresilient pressing member is an extension spring disposed between thesupport plate and the sidewall of the body to pull the support platetoward the sidewall, or a compression spring disposed between thesupport plate and the inclined plate to push the support plate towardthe sidewall of the cassette body.

BRIEF DESCRIPTION OF THE DRAWINGS

[0022] These and other objects and advantageous of the invention willbecome apparent and more readily appreciated from the followingdescription of the preferred embodiments, taken in conjunction with theaccompanying drawings of which:

[0023]FIG. 1 is a perspective view showing an interior of a paperfeeding cassette for a conventional image forming apparatus;

[0024]FIG. 2 is a side section view schematically showing the paperfeeding cassette of FIG. 1;

[0025]FIG. 3 is a perspective view showing an interior of a paperfeeding cassette in accordance with an embodiment of the presentinvention;

[0026]FIGS. 4 and 5 are side section views schematically showing amoving guide and a reciprocating unit of the paper feeding cassette ofFIG. 3; and

[0027]FIG. 6 is a perspective view schematically showing an appearanceof the paper feeding cassette of FIG. 3.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0028] Reference will now be made in detail to the present preferredembodiments of the present invention, examples of which are illustratedin the accompanying drawings, wherein like reference numerals refer tothe like elements throughout. The embodiments are described in order toexplain the present invention by referring to the figures.

[0029] Hereinafter, embodiments of the present invention will bedescribed in greater detail with reference to the accompanying drawings.

[0030] Referring to FIG. 3, a paper feeding cassette 200 for an imageforming apparatus according to an embodiment of the present inventionincludes a cassette body 210 having a containing space to contain sheetstherein, an inclined supporter 230 disposed in the cassette body 210,and a separation guide 220 supported on the inclined supporter 230. Thecassette body 210 is removably mounted in an image forming apparatusbody (not shown) and is provided with a pickup roller 240 picking-up thesheets stacked in the cassette body 210 and supplying the sheets to theimage forming apparatus body.

[0031] The separation guide 220 is disposed in the cassette body 210 inplural numbers, and comes into contact with a front end of a sheet beingpicked-up by the pickup roller 240 such that there occurs apredetermined friction resistance at a contacting area of the separationguide 220 and the sheet. At least one separation guide 220 is disposedto be able to contact selectively the front end of the sheet inaccordance with a type of the sheet. That is, the separation guide 220includes a fixing guide 222 and a moving guide 225, wherein the fixingguide 222 is fixedly disposed at the cassette body 210, and the movingguide 225 is movably disposed at the cassette body 210. Accordingly, themoving guide 225 selectively moves toward or away from a contact linewhere the front end of the picked-up sheet contacts the fixing guide222.

[0032] The separation guide 220 as constructed above is supported on theinclined supporter 230 which is disposed in the cassette body 210 at apredetermined slope with respect to the sheet. The inclined supporter230 includes an inclined plate 231 and a support plate 235 which supportthe fixing guide 222 and the moving guide 225, respectively. Theinclined plate 231 is fixed to the cassette body 210. The support plate235 reciprocates linearly within a space 215 that is formed between asidewall 211 of the cassette body 210 and the inclined plate 231. Thesidewall 211 is disposed at a rear side of the inclined plate 231.

[0033] Here, the inclined plate 231 is provided with at least oneopening 233. The opening 233 is a path through which the moving guide225 moves toward and back with respect to the front end of the sheet orthe contact line in accordance with a reciprocal movement of the supportplate 235. Provided in this embodiment are a plurality of inclinedplates 231, which are spaced from each other by a predetermineddistance. Accordingly, the opening 233 is regularly formed by a gap 233between the inclined plates 231 a or between the fixing guides 222.

[0034] As shown in FIG. 4, the moving guide 225 reciprocates linearly bya reciprocating unit 250 including the support plate 235 supporting themoving guide 225. At this point, the reciprocating unit 250 includes aguide portion 253 for guiding the support plate 235 to slidably movewithin the space 215, and a cam member 251 rotatably mounted in thecassette body 210 and disposed in the space 215, a side of the cammember 251 contacting a rear surface of the support plate 235. The cammember 251 rotates and controls the support plate 235 to reciprocatelinearly within the space 215 along the guide portion 253.

[0035] Furthermore, the reciprocating unit 250 includes a driving unitrotating the cam member 251 and a rotary shaft 255 transmitting arotation driving force from the driving unit to the cam member 251. Atthis point, the rotary shaft 255 is disposed across the space 215 alongthe rear surface of the support plate 235, and the cam member 51 isdisposed on the rotary shaft 255. Also, as shown in FIG. 6, the drivingunit rotatably driving the rotary shaft 255 includes a rotary lever 259disposed at an end of the rotary shaft 255 extended from the sidewall211 of the cassette body 210. Accordingly, a user manipulates the rotarylever 259 to rotate the cam member 251 in accordance with the type ofthe sheet stacked in the paper feeding cassette 200, thereby allowingthe moving guide 225 to come into contact with or be separated from thefront end of the picked-up sheet.

[0036] As shown in FIG. 4, the reciprocating unit 250 further includes aresilient recovering unit allowing the moving guide 225, which advancesto contact the front end of the sheet by the rotation of the cam member251, to separate automatically the front end of a thin sheet P2. Aresilient pressing member 257 is used as the resilient recovering unitand disposed inside the space 215 to press resiliently one of thesupport plate 235 and the cam member 251 in a direction of a contactpoint of the support plate 235 and the cam member 251. At this point,the resilient pressing member 257 includes a coil spring 257 connectingthe support plate 235 to the sidewall of the cassette body 210. The coilspring 257 functions as a tension spring to pull the support plate 235toward the sidewall 211. Accordingly, the support plate 235 maintains acontacting condition with the side of the cam member 251 regardless of aposition of the cam member 251, thereby reciprocating linearly along theguide portion 253 with the cam member 251 when the cam member 251rotates.

[0037] The paper feeding cassette 200 as constructed above is notlimited to this embodiment. For example, unlike the above embodiment inwhich a single support plate 235 is provided with a plurality of themoving guides 225, the support plate 235 may be provided in pluralnumbers to correspond to the respective moving guides 225. In this case,the cam member 251 is provided on the rotary shaft 255 in plural numbersto correspond to the respective support plates 235 and, accordingly, theguide portion 253 and the resilient pressing member 257 are alsoprovided in plural numbers to correspond to the respect support plates235.

[0038] Also, the rotary shaft 255 is rotatably driven by being connectedto another driving unit instead of the rotary lever 259, wherein theanother driving unit may be an electromotive motor disposed inside theimage forming apparatus (not shown) for an overall driving of mechanismsof the image forming apparatus body. Accordingly, after a paper typedetecting signal is input to a controller (not shown) by a user'sselection or a predetermined paper type detecting sensor, the controllercontrols the another driving unit to reciprocate automatically such thatthe support plate 235 reciprocates.

[0039] Also, various modifications are possible as well. For example,the resilient pressing member 257 may be a compression spring that isdisposed to connect the support plate 235 to the inclined plate 231, ora compression spring resiliently compressing the cam member 251 towardthe support plates 235.

[0040] Hereinafter, an operation of the paper feeding cassette of theimage forming apparatus according to another embodiment of the presentinvention will be described in detail with reference to the accompanyingdrawings.

[0041] As shown in FIG. 5, if a thick sheet P1 is stacked in thecassette body 210, the user manipulates the rotary lever 259 to move thesupport plate 235 toward an inner side of the space 215. Then, themoving guide 225 moves back toward the space 215 through the opening 233not to contact the thick sheet P1 such that a friction resistancebetween the separation guide 220 and the picked-up paper P1 becomesminimized. In this state, the pick-up roller 240 rotates to separate thesheet P1 one by one from the plurality of sheets P stacked in thecassette body 210 and supply the sheet to the image forming apparatusbody (not shown).

[0042] Meanwhile, as shown in FIG. 4, if the thin sheet P2 thinner thanthe thick sheet P1 in FIG. 4 is stacked in the cassette body 210, thefriction resistance occurred in the above state where the moving guide225 moves away from the inclined plate 231 toward the space 215 andwhere only the fixed guide contacts the thin sheet P2, is not sufficientto separate the thinner sheet P2 one by one. Therefore, in order toincrease the friction resistance, the user manipulates the rotary lever259 to move linearly the moving guide 225 toward the front end of thethinner sheet P2. Then, the moving guide 225 and the fixing guide 222simultaneously come into contact with the thin sheet P2 such that thereoccurs a higher degree of the friction resistance than that generated inFIG. 4. Accordingly, the thin sheet P2 is easily picked-up and separatedone by one.

[0043] Meanwhile, although this embodiment depicts that the fixing guide222 and the moving guide 225 have the same degree of surface roughness,it is understood that the invention is not limited thereto. That is, thevarious modifications are possible. For example, the moving guide 225may have a higher surface roughness than the fixing guide 225 and viceversa.

[0044] The paper feeding cassette 200 as described above according tothe present invention is provided with the separation guide 220generating the friction resistance by contacting the front end of thesheet P1 or P2, wherein the separation guide 220 includes the movingguide 225 disposed to contact selectively the sheet P1 or P2.

[0045] According to the above construction, the moving guide 225 ismanipulated to reciprocate linearly in accordance with the type of thesheet P1 or P2 such that the friction resistance between the sheet P1 orP2 and the separation guide 220 varies in a degree. Accordingly, avariation in the degree of the friction resistance according to the typeof the sheet P1 or P2 makes it easy to supply the sheet P1 or P2 one byone to the image forming apparatus body. Especially, in a case of thethick sheet P1, the cassette body 210 is prevented from jamming.

[0046] Although a few preferred embodiments of the present inventionhave been described, it will be understood by those skilled in the artthat the present invention should not be limited to the describedpreferred embodiments and that changes may be made in this embodimentwithout departing from the principles and sprit of the invention, thescope of which is defined in the claims and their equivalents.

What is claimed is:
 1. A paper feeding cassette for an image formingapparatus, comprising: a cassette body containing a sheet therein; aninclined plate fixedly disposed in the cassette body to come intocontact with the sheet; a fixing guide fixedly disposed in the cassettebody and supported on the inclined plate to contact the sheet; a movingguide movably disposed at the inclined plate to move toward and awayfrom a contact line where the fixing guide contacts the sheet; and areciprocating unit linearly reciprocating the moving guide.
 2. The paperfeeding cassette of claim 1, wherein the cassette body comprises a spaceformed between a rear surface of the fixing guide and a sidewall of thecassette body, and the reciprocating unit comprises: a support platemovably disposed within the space to support the moving guide; a guideportion movably supporting the support plate in a sliding manner; a cammember rotatably disposed within the space to contact a rear surface ofthe support plate to reciprocate the support plate; and a resilientpressing member resiliently pressing one of the support plate and thecam member in a direction of a contact point of the support plate andthe cam member.
 3. The paper feeding cassette of claim 2, wherein theinclined plate comprises an opening, and the moving guide selectivelymoves with respect to the contact line through the opening in accordancewith a reciprocal movement of the support plate.
 4. The paper feedingcassette of claim 2, wherein the reciprocating unit comprises a drivingunit and a rotary shaft disposed across the space to be rotated by thedriving unit, and the cam member is disposed on the rotary shaft.
 5. Thepaper feeding cassette of claim 4, wherein the driving unit comprises arotary lever disposed at an end of the rotary shaft extended from thesidewall of the cassette body.
 6. The paper feeding cassette of claim 4,wherein the driving unit comprises an electromotive motor disposedinside the cassette body being connected with the rotary shaft totransmit a rotation driving force to the rotary shaft.
 7. The paperfeeding cassette of claim 2, wherein the resilient pressing membercomprises an extension spring disposed between the support plate and thesidewall of the body to pull the support plate toward the sidewall. 8.The paper feeding cassette of claim 2, wherein the resilient pressingmember comprises a compression spring disposed between the support plateand the inclined plate to pull the support plate toward the sidewall ofthe cassette body.
 9. A paper feeding cassette for an image formingapparatus, comprising: a cassette body containing a sheet and having apickup roller picking up the sheet; an inclined support disposed to beinclined with respect to the sheet contained in the cassette body; and aseparation guide supported by the inclined support to generate a firstfriction resistance and a second friction resistance to separate thesheet from the cassette body when contacting a front end of the sheetpicked up by the pickup roller in response to a type of the sheet. 10.The paper feeding cassette of claim 9, wherein the type of the sheetcomprises a thickness of the sheet.
 11. The paper feeding cassette ofclaim 9, wherein the separation guide generates the first frictionresistance when the type of sheet has a first thickness, and generatesthe second friction resistance when the type of sheet has a secondthickness smaller than the first thickness.
 12. The paper feedingcassette of claim 11, wherein the first friction resistance is smallerthan the second friction resistance.
 13. The paper feeding cassette ofclaim 9, wherein the separation guide has a first surface roughness anda second surface roughness and uses one of the first surface roughnessand the second surface roughness to generate the first frictionresistance or both of the first surface roughness and the second surfaceroughness to generate the second friction resistance in response to thetype of the sheet.
 14. The paper feeding cassette of claim 9, whereinthe separation guide comprises a moving guide movably disposed on theinclined support to contact selectively the front end of the sheet, andchanges the first friction resistance to the second friction resistancein response to a contact between the moving guide and the front end ofthe sheet.
 15. The paper feeding cassette of claim 9, wherein theseparation guide comprises a fixed guide having a first surfaceroughness and a moving guide having a second surface roughness, and thefixed guide contacts the front end of the sheet picked up by the pickuproller to generate the first friction resistance with the first surfaceroughness while the moving guide selectively contacts the front end ofthe sheet to generate the second friction resistance.
 16. The paperfeeding cassette of claim 15, wherein both the fixed guide and themoving guide contact the front end of the sheet to generate the secondfriction resistance with the first surface roughness and the secondsurface roughness when the moving guide contacts the front end of thesheet.
 17. The paper feeding cassette of claim 16, wherein the movingguide does not contact the front end of the sheet when the type of thesheet represents a first thickness, and contacts the front end of thesheet when the type of the sheet represents a second thickness smallerthan the first thickness.
 18. The paper feeding cassette of claim 9,wherein the inclined support comprises an inclined plate fixed on thecassette body, an opening formed in the inclined plate, and a supportplate movably disposed in the opening, and the separation guidecomprises: a fixed guide formed on the inclined plate to contact thefront end of the sheet regardless of the type of the sheet; and a movingguide formed on the support plate to contact selectively the front endof the sheet in response to the type of the sheet.
 19. The paper feedingcassette of claim 18, wherein the cassette body comprises a sidewallspaced-apart from the inclined plate and a guide portion connectedbetween the sidewall and the inclined plate to guide the moving guide tomove toward a plane, on which the inclined plate is disposed, and awayfrom the plane of the inclined plate.
 20. The paper feeding cassette ofclaim 19, wherein the cassette body comprises another guide portionconnected between the sidewall and the inclined plate, and the movingguide moves in a direction parallel to one of the guide portion andanother guide portion.
 21. The paper feeding cassette of claim 19,wherein a movement of the moving guide forms another plane, and theplane of the inclined plate and another plane of the moving guide aredisposed perpendicular to each other.
 22. The paper feeding cassette ofclaim 19, wherein the cassette body comprises: a reciprocating unitdisposed in the cassette body to control the moving plate to move towardand away from the plane.
 23. The paper feeding cassette of claim 22,wherein the reciprocating unit comprises a driving unit rotatablymounted in the cassette body to push the moving plate toward the plane.24. The paper feeding cassette of claim 23, wherein the reciprocatingunit comprises a resilient member coupled between the moving plate andthe cassette body, and the moving plate is biased to move away from theplane in response to the resilient member and toward the plane inresponse to a movement of the driving unit.
 25. The paper feedingcassette of claim 9, wherein the inclined support comprises a pluralityof inclined plates fixed on the cassette body, openings formed betweenthe inclined plates, and support plates movably disposed in respectiveones of the openings, and the separation guide comprises: fixed guidesformed on respective ones of the inclined plates to contact the frontend of the sheet; and moving guides formed on respective ones of thesupport plate to contact selectively the front end of the sheet inresponse to the type of the sheet.
 26. The paper feeding cassette ofclaim 25, wherein the cassette body comprises a sidewall spaced-apartfrom the inclined plate and a guide portion connected between thesidewall and respective ones of the inclined plates to guide respectiveones of the moving guide to move along the guide portion forward to aplane, on which a major plane of one of the inclined plates is disposed,and back toward the sidewall from the plane.
 27. The paper feedingcassette of claim 26, wherein the cassette body comprises another guideportion connected between the sidewall and respective ones of theinclined plates, and the moving guide moves in a direction parallel toone of the guide portion and another guide portion.
 28. The paperfeeding cassette of claim 26, wherein the cassette body comprises: areciprocating unit disposed in the cassette body to control respectiveones of the moving plates to move toward and away from the plane.
 29. Amethod in a paper feeding cassette of an image forming apparatus havinga cassette body and an inclined plate inclined with respect to a sheetcontained in the cassette body, the method comprising: picking up thesheet from the cassette body toward the inclined plate; and generatingone of a first friction resistance and a second friction resistance toseparate the picked-up sheet from the cassette body in response to athickness of the picked-up sheet by using an inclined support having afirst surface roughness and a second surface roughness.
 30. The methodof claim 29, wherein the inclined support comprises a fixed guide havingthe first surface roughness and contacting a front end of the picked-upsheet and a moving guide having the second roughness and selectivelycontacting the front end of the picked-up sheet, and the generating ofthe one of the first friction resistance and the second frictionresistance comprises: controlling the moving guide to move toward thesheet to contact a front end of the picked-up sheet to generate thesecond friction resistance by adding the first surface roughness of thefixed guide and the second surface roughness of the moving guide; andcontrolling the moving guide to move away from the sheet no to contactthe front end of the picked-up sheet to generate the first frictionresistance with the front end of the picked-up sheet by using the firstsurface roughness of the fixing guide.